A substrate with a transparent electrode, in which a transparent conductive film is provided on a transparent substrate such as a transparent film or glass, is used for a touch panel incorporated in a mobile phone, a game machine, a computer or the like, or a display device of electronic paper, a PDA or the like. As a material of the transparent conductive film of the substrate with a transparent electrode, a conductive oxide such as indium tin oxide (ITO) is widely used. When the substrate with a transparent electrode is used for position detection of a capacitance touch panel, the transparent conductive film (transparent electrode) is patterned. Each pattern electrode is electrically connected to control means such as an IC through a routing wiring provided on a frame edge region at the periphery of a display, and position detection is performed based on a capacitance of each pattern electrode. When the resistance of the electrode increases, the sensitivity of position detection and the response speed decrease, and therefore the demand for a transparent conductive electrode having a lower resistance has increased.
On the other hand, with higher definition of displays, it has been required to reduce the pattern widths of electrodes for improving accuracy of position detection. A conductive oxide such as ITO has a large absorption of light having a wavelength of 400 nm or less, so that when the thickness increases, the screen image is colored due to absorption of short-wavelength light, leading to deterioration of visibility. Thus, the thickness of the transparent conductive film is preferably as small as possible. However, when the width and the thickness of the electrode decrease, the cross-sectional area decreases, leading to an increase in resistance of the electrode. When the display area increases, the distance between frame edges increases, and therefore the distance of the electrode increases, so that even though the resistivity of the transparent electrode remains the same, the resistance of the electrode increases.
Thus, in order to produce a display having a high definition and a large area without reducing the position detection sensitivity and the response speed, it is necessary to form a transparent conductive film having a lower resistivity on a substrate. For example, Patent Document 1 describes that when a film is formed by sputtering on a glass substrate heated to 200° C. or higher while a surface magnetic field of a target is adjusted, a low-resistance ITO film having a resistivity of 1.1×10−4 to 1.2×10−4 Ωcm is obtained.
As a transparent substrate, a resin substrate (film) has come into use in place of glass from the viewpoint of weight reduction of devices, ease of handling, high formability of a transparent conductive film by sputtering, and so on. For example, Patent Document 2 discloses that when an oxygen partial pressure, a water partial pressure and so on during deposition are controlled while the content of tin oxide in a target used for deposition by sputtering is set to 8% by weight or less, a low-resistance ITO film having a resistivity of about 3×10−4 to 4×10−4 Ωcm can be formed on a resin substrate.